Possibly the worst chat-up line I've ever had the misfortunate of overhearing was when a man in a Brooklyn bar sidled up to a girl and complimented her on her Jawbone. "I've started to wear a Basis as well as a Jawbone," he sniffed, extending his wrist for inspection. "The Jawbone is stylish, sure, but the Basis is a more serious piece of hardware. I really like how its galvanic skin response sensor tracks my perspiration levels." The girl made a polite little noise then swiftly removed herself to the other end of the room.

There are a couple of things to be learned from this sad story. The first is that enthusing about how you like to quantify your sweat statistics is not a good way to get laid. Even in Brooklyn. The second is that the proliferation of wearable fitness devices such as Nike's Fuelband, Jawbone Up, and the Basis band, coupled with the increasing popularity of health and fitness apps, has pushed self-tracking from niche geek activity and into the mainstream.

A recent study by the Future Laboratory and Confused.com found that about 60% of 18- to 34-year-olds in the UK have used a self-quantifying app or service to monitor their fitness levels, mental health and sleep patterns. These figures are mirrored across the pond. According to a Pew report, 60% of US adults say they track their weight, diet or exercise routine. And these numbers are rising. Indeed, it's highly probable that you or someone you know will be have received or given some sort of wearable fitness product this Christmas season.

Evangelists of self-tracking technology proclaim that through data lies enlightenment. Measuring ourselves, they say, will help us understand ourselves. We will all end up several percentage points healthier and happier. However, I'm not sure this is right. While it is true that self-tracking can help push people into making positive lifestyles changes, it could also be argued that the growing popularity of this sort of technology is normalising neurotic behaviour.

When I was a teenager I went through a brief phase of compulsive self-quantification. It was called anorexia. I counted every calorie, weighed myself obsessively and exercised fanatically. For about a year my life was a running tally of energy-in and energy-out and I would diligently feed all these numbers into a sort of anorexia algorithm; regularly adjusting different variables in order to maximise weight-loss efficiencies. The end result was that I weighed six stone and my hair fell out in clumps. I looked grim, but I did get a good grounding in data analytics.

This was all a long time ago and I'm now fully recovered. This is in no small part due to the fact that I actively avoid weighing myself and try not to count calories. It took me a long time to stop seeing food as a spreadsheet of numbers and start thinking about it as nutrition. It would have taken me even longer if the sort of self-tracking technology that is ubiquitous today was available when I was ill. Dr Kimberly Dennis, a psychiatrist who specialises in eating disorder treatment, estimates that about 75% of her young-adult patients use their phones in a way that enables their eating disorders. Apps that facilitate calorie-counting and food-logging are an anorexic's best friend and worst enemy. With society increasingly embracing a sort of "techorexia" that rewrites compulsive behaviour as healthy, it is becoming easier for people with serious eating disorders to pretend there's nothing wrong.

All of this is not to say that strapping on a Jawbone or monitoring your food intake and exercise with some sort of mobile app is inherently harmful. Indeed, for some people, this sort of self-tracking can be incredibly beneficial. I just worry that as our lives become more data-driven, we are becoming overly fixated on the value of the variables that we can measure. In our growing obsession with counting everything and anything, it is possible that we are losing track of what really counts.